Integrated Amps

Marantz makes some pretty good integrateds, better than many of the non-japanese designs simply due to Marantz (like Yamaha, Sony, Luxman and Denon) knowing how to design a quiet circuit. I haven’t heard the Billie. It gets good reviews but I’ve seen quite a few of the mkII version on the pre-owned market already—unusual for what I imagine is a low-volume product. 
 

For integrateds, I haven’t encountered any that outperform the Yamaha A-S2200 or A-S2100 for their street price. They combine the good traits of tubes and solid state better than any of the hybrid tube/SS products I’ve used/owned. Usually with the latter, instead of the “best of both worlds,” you instead get the worst of both. 

+1, Musical Fidelity M-6Si integrated amp.

Simply stated, I know when music sounds good and does not. Obviously (based on my MANY amp changes), I am not happy with amplifiers that do not sound good.

I own the Musical Fidelity M-6Si integrated amp. I am VERY surprised it sounds this good. The M6si offers excellent performance, facilities, and power. As per the Musical Fidelity web site “Internally, the M6si is configured as 2 independent monobloc power amps with a separate preamp. It is, in fact, a preamp with 2 monobloc power amps that just happen to share the same casework. The M6si has 220wpc. It has very low distortion, outstanding noise ratio and extremely flat frequency response”.

My speakers are the PMC Twenty5.6. I contacted The Music Room, and they recommended the Musical Fidelity M-6Si integrated amp. I am VERY surprised it sounds this good. The M6si offers excellent performance, facilities, and power.

I am very happy with my Musical Fidelity M-6Si integrated amp and have STOPPED looking for the next amp.

My friend said synergy between components is what makes am an audio system sound great. I hope this helps. Obviously, in my system the Musical Fidelity M-6Si integrated amp is a great fit for my PMC speakers.

I also suggest you look at the NAIM SuperNate integrated amp It is also very good.

More info on MF M6Si amp link

Luxman!

Another two cents:  Of all the amps the OP mentioned, the only one I've ever spent any serious seat-time with (i.e.  approximately 2 hours) when I was auditioning for a two-channel system speaker upgrade several years ago was the MF m6si.  That is one fantastic amp, provided it is matched to the right speakers.  I listened to it with a couple models of Paradigm towers.  Forget the model numbers but they were in the 3K and 4K price points.

I went from a Marantz PM8005 to a McIntosh MA352. A big change in budget, but the 200w hybrid integrated really paired well with my Dynaudios.  Since upgrading I'm not wanting for power, bass, details and soundstage. The MA352 does have dual subwoofer outputs if you want to add 2 SWs, but I found the speakers alone delivered all the musical bass needed in a 2 channel system.